This species breeds in the northern taiga of Europe and Asia and winters on sheltered coasts or inland lakes. It nests in tree holes, such as old woodpecker nests. The Smew has a hooked tip and serrated edges to its bill to help it catch fish, which it does by diving.
The Smew is shy and flushes easily when disturbed.
The drake Smew, with its 'cracked ice' appearance is unmistakeable, and looks very black-and-white in flight. The female is a grey bird with a chestnut forehead and crown, which can be confused at a distance with Ruddy duck. It has oval white wing-patches in flight.